536 AXATOMICAL TECBNOLOGT. 



Palpebra dorsalis. — The dorsal fsnperior or upper) eyelid. The dorsal lid does not 

 contain a tarsal cartilage as in man (Quain, A, II, 584), and there are no eyelashes (cilia), 

 (§ 1400). 



Palpebra ventralis (Plpbr. vntr.). — The ventral (inferior) or lower lid, like the dorsal, 

 possesses no lashes (§ 1400). 



Pili tactiles. — Tactile hairs. The bulb of one is shown to indicate its great size and 

 deep implantation (§ 1396). 



Plicae ciliares (P. c.) s. processus cUiares, ciliary plicae or processes. — They are foldings 

 of the choroidea. The abbreviation is written on one shown in its full extent. It is approx- 

 imately triangular in outline, and to its tip is attached the eonula of Zinn , and into it pass 

 many strong bands forming part of the suspensory ligament. The folds bifurcate caudad 

 and gradually merge into the general surface of the choroid (§ 14'32i. 



Retina. — The nervous tunic of the eye. It is the ental of the three coats. In the 

 figure its cut edge is crossed by lines, and on the ventral side it is drawn away from the 

 choroid and toward the center of the eye (§ 1424). 



Sclerotica. — This with the cornea forms the ectal coat of the eye. In the cat it is 

 very thin except opposite the iris and ciliary plicss. Here it is thickened and has been 

 termed, provisionally, Zona aWa (§ 1421). 



Tapetum. — The brilliantly colored part of the ental surface of the choroidea (§ 1425). 



Vitreum. — The vitreous body or vitreous humor. It fills the entire space caudad of 

 the lens and zonula of Zinn. It is clear and somewhat jelly-like. The canal of Petit is 

 merely an interval between the vitreum and the zonula. As it is not supposed to exist 

 during life, and certainly did not appear in the sections of the frozen eye, it has been 

 omitted. 



Zona alba (Z. a.). — This is a thickening of the sclerotica giving firmness to the eye- 

 ball. Into its caudal edge are attached the recti muscles (§§ 1407, 1408). 



Zonula Zinnii (Z. Z.) s. Ligamentum suspensorium lentis. — The suspensory ligament 

 in the cat is attached to the lens capsule at the edge of the lens and passes not only to the 

 summits of the ciliary processes, but into their substance as shown in the figure. More- 

 over, there is an especially strong part of the ligament opposite the summit of each ciliary 

 process. 



AURIS— ORGAXUil AUDITUS— EAR. (Fig. 127, 128.) 



General References. — Gray, A, 729 ; Quain, A, II, 626 ; Dalton, A, 554 ; Flint, A ; 

 Foster and Langley, A, 201 ; Foster, A, 574 ; Hyrtl, A, 413 ; Leyh, A, 338 ; Strieker, A, 

 950 ; Chauveau, A, 880 ; Chauveau (Fleming), A, 846 ; Owen, A, III, 235 ; Gurlt, A, 79. 

 799 ; Milne-Edwards, A, XII, 1 ; Bernstein, A, 164. 



Instruments and Material. — Watch spring saw ; nippers ; dissecting instruments 

 (g 181) ; tripod magnifier ; 15 per cent, glycerin ; cat's head ; macerated skull prepared as 

 in Fig. 57. 



§ 1431. Auris, ear. — This, the organ of hearing in the cat as in 

 the higher animals generally, is composed of three parts, two of 

 which (labyrinth and tympanum) are completely encased in bone. 



(A) Auris ectalis (externa), ectal or external ear. — This includes 

 the external ear, commonly so called, which is partly cartilaginous, 

 and the meatus auditorius ectalis (externus\ a partly bony canal 



